Ubuntu Manpage: pvm_psend - Pack and send data in one call.

NAME

       pvm_psend - Pack and send data in one call.

SYNOPSIS

       C    int info = pvm_psend( int tid, int msgtag, char *buf,
                                  int len, int datatype )

       Fortran   call pvmfpsend( tid, msgtag, buf, len, datatype,
                               info )

PARAMETERS

       tid     Integer task identifier of destination process.

       msgtag  Integer message tag supplied by the user.  msgtag should be >= 0.

       buf     Pointer to a buffer to send.

       len     Length of buffer (in multiple of data type size).

       datatype
               Type of data to which buf points (see below).

       info    Integer status code returned by the routine.

DESCRIPTION

The routine pvm_psend takes a pointer to a buffer buf its length len and its data type datatype and sends
this data directly to the PVM task identified by tid. msgtag is used to label the content of the
message. If pvm_psend is successful, info will be 0. If some error occurs then info will be < 0.

pvm_psend data can be received by pvm_precv, pvm_recv, pvm_trecv, or pvm_nrecv.

The pvm_psend routine is asynchronous. Computation on the sending processor resumes as soon as the
buffer is safe for reuse. This is in contrast to synchronous communication, during which computation on
the sending processor halts until the matching receive is executed by the receiving processor.

In C the datatype parameter must be one of the following, depending on the type of data to be sent:
[Version 3.3.0 - This parameter only determines message length, not data conversion. It only sends raw
bytes]
datatype Data Type
PVM_STR string
PVM_BYTE byte
PVM_SHORT short
PVM_INT int
PVM_FLOAT real
PVM_CPLX complex
PVM_DOUBLE double
PVM_DCPLX double complex
PVM_LONG long integer
PVM_USHORT unsigned short int
PVM_UINT unsigned int
PVM_ULONG unsigned long int

In Fortran the same data types specified for pack should be used.

The PVM model guarantees the following about message order. If task 1 sends message A to task 2, then
task 1 sends message B to task 2, message A will arrive at task 2 before message B. Moreover, if both
messages arrive before task 2 does a receive, then a wildcard receive will always return message A.

pvm_psend does not affect the state of the current outgoing message buffer (created by pvm_initsend and
used by pvm_send).

WARNINGS

       In  some  versions  of  PVM  (CM5, I860 and PGON), messages sent using pvm_psend must be received only by
       pvm_precv, likewise those sent with pvm_send must  be  received  by  pvm_recv,  pvm_nrecv  or  pvm_trecv.
       pvm_psend  is  not compatible with pvm_recv (nor pvm_send with pvm_precv).  In addition, pvm_probe is not
       interoperable with pvm_psend.

       This problem occurs because nonstandard  message  headers  are  used  for  efficiency  in  the  pvm_psend
       function.  In the generic Unix version of PVM, the calls are fully interoperable.

       The message tag space is shared between pvm_send and pvm_psend, so you must be careful to avoid selecting
       the wrong message (for example by using a wildcard to match the message).

EXAMPLES

       C:
           info = pvm_psend( tid, msgtag, array, 1000, PVM_FLOAT );

       Fortran:
           CALL PVMFPSEND( TID, MSGTAG, BUF, CNT, REAL4, INFO )

ERRORS

       These error conditions can be returned by pvm_psend

       PvmBadParam
              giving an invalid tid, msgtag, or datatype.

       PvmSysErr
              pvmd not responding.